It has for many decades been known to use toothed wheels to tune the strings of musical instruments. Two of the most recent mechanisms of this type involve headless guitars or headless bass guitars. These are shown by U.S. Pat. Nos. 4,693,160 and 4,712,463.
U.S. Pat. No. 4,693,160 teaches a mechanism in which there is constant meshing between worm teeth and the teeth of a worm wheel. No means is provided for permitting direct manual operation of the worm wheel--without using the worm--so as to rapidly obtain gross or coarse adjustments.
U.S. Pat. No. 4,712,463 provides a mechanism which permits direct manual operation of a toothed wheel that is not a worm wheel. This is done by providing an element in releasable relationship on an intermediate member between the toothed wheel and a fine adjustment screw. Although this mechanism is on the market, and works well, it has disadvantages one of which is that the amount of fine tuning which can be achieved is not unlimited for any particular coarse-tuning setting. Thus, it can occur that the mechanism runs out of travel--during fine tuning--after a certain coarse adjustment has been made; then, it is necessary to release the mechanism and repeat the coarse and fine tuning operations.
It has also, for many decades, been conventional in electric guitars and basses to provide bridges that can be adjusted both vertically and longitudinally of the string, so as to (a) change string height, and (b) achieve correct intonation. Many types of constructions have been patented for these purposes. However, no mechanism known to applicants has great versatility and speed of adjustment plus an extremely low energy requirement for effective, accurate locking and unlocking (clamping and unclamping) of the bridge mechanism.